I am looking at the CTD, and am a current Volkswagen owner. I don't own a TDI however, I have a GTI.
Volkswagens are almost always fun to drive, but mine and all of my friends' VWs have been bottomless money pits. The older TDIs have a great reputation for reliability; the new ones not so much. The Jettas and Golfs have the infamous HPFP and intercooler icing problem, plus the general electronic issues you can expect on any VW. The Passats have so far been pretty hardy I believe. Also, if you're buying an auto trans, VWs DCT is not particularly reliable but there is always the manual available.
The new Mk7 generation is fixing the intercooler icing issues, but not the HPFP if I recall. They're also adding the DPF and new modular chassis system to lower manufacturing costs and purchase price, and are moving production to Mexico. VW does very well around the world sales wise, but they're slipping badly in the US so the cost cutting is their attempt to bring customers in.
Reliability is important to me so I have been taking a more serious look at the CTD which seems to be a pretty solid platform.